Why are there no red dwarf stars of low metallicity?

With all the fuel gauges pegged to full, a critical parameter's worth of confusion is removed. Red dwarfs of a particular mass should form a well-defined one-parameter sequence in the Hertzsprung Russell diagram, and that parameter should be metallicity. read more

There are lots of red dwarfs of moderate metallicity (Population II) in globular clusters that we can see at tens of thousands of light years. We cannot see early low-metallicity Population III stars. read more

Measuring red dwarf metallicities is a challenge. First, the stars are dim, but spectroscopic determinations of metallicity require excellent spectra, which in turn require lots of photons from a star. Second, the stars are so cool that atoms in the stellar atmospheres join to form molecules, which complicate the analysis. read more

The fact that red dwarfs and other low-mass stars still remain on the main sequence when more massive stars have moved off the main sequence allows the age of star clusters to be estimated by finding the mass at which the stars move off the main sequence. read more